This invention relates to a heat-dissipating grease composition, and more specifically, to a heat-dissipating silicone grease composition suitable for use over a long period of time.
Heat-dissipating silicone greases based on silicone grease and containing various kinds of powders as fillers, are known in the prior art (Tokko Sho 52-33272, Tokko Sho 59-52195, Tokkai Sho 52-125506, Tokkai Sho 57-36302, Tokkai Sho 62-43492, Tokkai Hei 2-212556 and Tokkai Hei 3-162493 (Koho)).
However, when used over a long period of time, the base oils in these silicone greases sometimes bled so that their heat-dissipating properties declined, or led to poor connections in electrical contacts.
As a result of intensive studies aimed at solving the above problem, the inventors found that the exudation of base oil could be suppressed by using a specific organopolysiloxane as the base oil, and thereby arrived at this invention.
It is therefore an object of this invention to provide a highly reliable silicone grease composition for heat dissipation having stable thermoconductive properties over a long period of time, which does not exude oil, and which does not lead to contact defects.
The above object is attained by a heat-dissipating silicone grease composition comprising:
(A) 100 weight parts of an organopolysiloxane having a thixotropicity degree xcex1 of 1.03-1.50 and a viscosity at 25xc2x0 C. of 100-1,000,000mm2/s, and
(B) 100-2,000 weight parts of a thermally conductive inorganic filler having an average particle diameter of 0.1-100 micrometers.